Printer

ABSTRACT

A printer having restraining members each driven by electromagnet means to release an associated engaging member from restrainment and thereby to allow said engaging member to stop the rotation of an associated type wheel, wherein said restraining member comprises a first restraining member which moves in a direction to get close to a rotary shaft of said engaging member and releases said engaging member from restrainment and a second restraining member which moves in a direction to move away from the rotary shaft of said engaging member and releases said engaging member from restrainment.

United States Patent [191 Mizutani et al.

[4 Jan. 21, 1975 PRINTER [75] Inventors: Nagao Mizutani; Masamitsu Nojima; Yasuo Okawara, all of Tokyo, Japan [73] Assignee: Citizen Tokei Company Limited,

Tokyo, Japan [22] Filed: Feb. 2, 1973 [21] Appl. No.: 328,985

[30] Foreign Application Priority Data Feb. 4, 1972 Japan 47-13127 [52] US. Cl ..101/99,101/95,101/110 [51] Int. Cl B4lj 1/22 [58] Field of Search 101/93 C, 95, 99, 110

[56] References Cited UNITED STATES PATENTS 3,289,575 12/1966 Wassermann 101/93 C 3,307,676 3/1967 Hakerson 101/1 10 X 3,422,754 l/l969 Bakardjiev et al lOl/l 10 X 3,636,871 l/l972 Speicher l0l/ll0 X 3,664,259 5/1972 Weinkle l0l/99 3,669,016 6/1972 Kittel 101/110 3,732,812 5/1973 Bremner 101/99 Primary ExaminerEdgar S. Burr Assistant ExaminerEdward M. Coven Attorney, Agent, or FirmElliott I. Pollock [57] ABSTRACT A printer having restraining members each driven by electromagnet means to release an associated engaging member from restrainment and thereby to allow said engaging member to stop the rotation of an associated type wheel, wherein said restraining member comprises a first restraining member which moves in a direction to get close to a rotary shaft of said engaging member and releases said engaging member from restrainment and a second restraining member which moves in a direction to move away from the rotary shaft of said engaging member and releases said engaging member from restrainment.

2 Claims, 12 Drawing Figures PATENTEDJANZIIQYF 3.861.302

' sum ear 6 PATENTED JAN?l 3.86 l 302 sum 50F s PATENTEDJANZT I915 3.861.302

' sum 5 or 6 F/alz' PRINTER This invention relates to a printer so designed that symbols, characters, etc. desired to be typed are selected and printed by electric signals.

Conventional printers have been not fully satisfactory in respect of the requirement that a large amount of information is printed in a limited area, without sacrificing the size of the printed characters, easiness of reading, printing speed, etc.

Namely, in the conventional printers, a considerably large space has been required for the accommodation of type selecting means and it has been inevitable that a space larger than necessary for reading the printed characters is formed between adjacent ones of said printed characters. This is because reducing arbitrarily the size of electromagnets required for the selection of characters will result in a lowered reliability of the character selecting operation and hence is subjected to a limitation.

As a solution to such problem, there has been proposed a single element type printer which prints characters one after another sequentially, or a discharge type printer, but either type has had the disadvantage that the printing speed is low or the printed characters are hardly legible.

It is, therefore, the object of the present invention to provide a printer which enables the spaceinterval of the printed characters or the so-called character pitch to be reduced and yet enables a sufficiently large space to be secured for the accommodation of electromagnet means, and further is highly reliable in the character selecting operation, not at the sacrifice of the character size.

The present invention will be described by way ofexample hereunder with reference to the accompanying drawings, in which:

FIG. I is a side view of an embodiment of the invention, showing the state of a printing mechanism at a column where a first restraining member is located, before the printing operation;

FIG. 2 is a side view of the state of the mechanism shown in FIG. 1 at the time of the printing operation;

FIG. 3 is a side view showing the state of a printing mechanism at a column where a second restraining member is located, before the printing operation;

FIG. 4 is a side view showing the state of the printing mechanism shown in FIG. 3 at the time of the printing operation;

FIG. 5 is a perspective view of the restraining members and electromagnet means as assembled;

FIG. 6 is a vertical sectional view of the essential portion of the assembly shown in FIG. 5;

FIG. 7 is a side view showing the state, before the printing operation, of a printing mechanism having electromagnet means arranged in a position substantially in point symmetry with the electromagnet means shown in FIG. 3;

FIG. 8 is a side view showing the state, before the printing operation, of a printing mechanism having electromagnet means arranged in a position substantially in point symmetry with the electromagnet means shown in FIG. 1;

FIG. 9 is a side view showing the manner of engagement between the restraining member and the engaging member;

FIG. 10 is an exploded perspective view of the essential portion of the printing mechanism;

FIG. 11 is a perspective view of the essential portion of another embodiment of the invention; and

FIG. 12 is a side view partially in section and showing the restraining members of the assembly shown in FIG. 11.

An embodiment of the present invention will be described hereunder with reference to the drawings. Referring to FIG. 1, a plurality of selector wheels 1 are rotatably mounted on a shaft 2 in side by side relation. Each selector wheel 1 has formed along the outer periphery thereof a number of ratchet teeth In and a number of teeth 1b, and also has an arcuate slot 1c formed therein. A drive bar 3 is extended through the arcuate slots 10 of the respective selector wheels 1, which is caused to make a reciprocal motion about the shaft 2, following a cam (not shown) driven from a prime mover (not shown). A clutch member 4 is rotatably mounted on a pin 5 provided on the selector wheel 1 and urged to rotate in a counterclockwise direction by a U-shaped spring 7, with a recess 4a formed therein being in engagement with the drive bar 3, said U- shaped spring 7 being anchored at one end to a pin 6 provided on said selector wheel 1. The selector wheel 1 is also provided with a fixed pin 8 thereon, which will limit the counterclockwise rotation of the clutch member 4 when said clutch member 4 is released from engagement with the drive bar 3. A type wheel 9 carries types 9b on the outer faces of teeth 9a provided thereon for meshing engagement with the teeth lb of the selector wheel 1, and is rotatably mounted on a shaft 10. Reference numeral 11 designates a ribbon, 12 a typing paper and 13 a platen. A positioning member 14 is driven by a cam (not shown), after the selection of a type, to move into the recessed portion between the teeth 9a of each type wheel 9 and thereby to bring the type wheel 9 into a position in registration with the other type wheels.

A stopper 15 is provided to limit a reverse rotation of each selector wheel 1 after a typing operation and thereby to align said selector wheel 1 with the other selector wheels. An engaging member 16 has a pawl 16a and a projection 16b. A plurality of such engaging members 16 are rotatably mounted on a shaft 17 in side by side relation. Each engaging member 16 is urged to rotate in a counterclockwise direction by a spring 18 anchored at one end to the stopper 15, with said projection 16b abutting against a roller 20 carried on a first restraining member 19A to be described later, and is held against rotation by said roller 20. The first restraining member 19A is one of restraining members 19 shown in FIG. 5, which is rotatably mounted on a shaft 21 and urged to rotate in a direction to move away from the shaft 17 of the engaging member 16 by a spring 22, with the other end abutting against a stopper 23. The aforesaid roller 20 is rotatably mounted on a pin 20a (see FIG. 10) provided at one end of the first restraining member 19A. A magnetic strip 24 is secured to the first restraining member 19A and further, a magnetically insulating plate 25 consisting of a nonmagnetic material, such as stainless steel, is secured to said magnetic strip 24 to ensure disengagement of said magnetic strip 24 from electromagnet means 26A when said electromagnet means 26A is demagnetized. The electromagnet means 26A is fixedly supported by support rods 27 and, when a signal is applied thereto, at-

tracts the magnetic strip 24, causing the first restraining member 19A to rotate in a direction to get close to the shaft 17 of the engaging member 16. Reference numeral 28 designates a printed circuit board and 29 designates an anchor rod to which one end of the spring 22 is anchored.

In FIG. 3, reference numeral 198 designates a second restraining member arranged adjacent the first restraining member 19A shown in FIG. 1 (see FIG. 5), which has a roller 20, a magnetic strip 24 and a magnetically insulating plate 25, and is urged by a spring 22 to rotate in a direction opposite to the direction in which the first restraining member 19A is urged to rotate, namely, in a direction to move toward the shaft 17 of the engaging member 16 and abutting against a stopper 23. Second electromagnet means 26B is arranged in a position substantially in axial symmetry with the first electromagnet means 26A and, when a signal is applied thereto, attracts the magnetic strip 24, causing the second restraining member 19B to rotate in a direction to move away from the shaft 17 of the engaging member 16.

The restraining members 19A, 19B and electromagnet means 26A, 268 may be arranged alternately in numbers corresponding to the desired number of columns. Since the restraining members 19A, 19B are arranged such that adjacent ones thereof move in opposite directions to each other, the electromagnet means 26A can be arranged striding over the second restraining member 19B and the electromagnet means 268 can similarly be arranged striding over the first restraining member 19A, as shown in FIG. 6. Therefore, the electromagnet means 26A, 268 can be accommodated in a narrow space, without deliberately making small the size of said electromagnet means. Further, by arranging the restraining members 19A, 198 such that they move in opposite directions to each other, as in this embodiment, it becomes possible to arrange the adjacent electromagnet means 26A and adjacent electromagnet means 26B respectively in close contact with each other as shown in FIG. 6 and thereby to reduce the space occupied by said electromagnet means 26A, 26B. Instead of using the arrangement shown in FIG. 3 for driving the restraining member 19 in a direction to move away from the shaft 17 of the engaging member 16, the arrangement may be made as shown in FIG. 7, in which electromagnet means 26C is arranged in a position substantially in axial symmetry with the electromagnet means 268 and a restraining member 19C having a magnetic strip 24 secured thereto is arranged in a position opposite to said electromagnet means 26C to be driven thereby. Similarly, instead of using the arrangement shown in FIG. 1 for driving the restraining member 19 in a direction to get close to the rotary shaft 17 of the engaging member 16, the arrangement may be made as shown in FIG. 8, in which electromagnet means 26D is arranged in a position substantially in axial symmetry with the electromagnet means 26A and a restraining member 19D having a magnetic strip 24 secured thereto is arranged in a position opposite to said electromagnet means 26D to be driven thereby.

The printer of the construction described above will operate in the following manner: Namely, in FIG. 1, when the prime mover is set in motion, the drive bar 3 starts moving in the direction of the arrow A, following the cam driven from said prime mover. In this case, the selector wheels 1 are also rotated all at once integrally with the drive bar 3, each through the associated clutch member 4, and further the type wheels 9 are rotated by the teeth 1b of the respective selector wheels I. Type position detector means (not shown) is actuated con currently with the rotation of the type wheel 9 to detect the particular type 9b of each type wheel 9 which is in a typing position. The detected type is collated with the information stored in memory means (not shown). which in turn sends a signal through the printed circuit board 28 to the electromagnet means for the column matching with the type, e.g. the electromagnet means 26A. The electromagnet means 26A, when applied with the signal, attracts the associated magnet strip 24, so that the first restraining member 19A makes a pivotal movement in a direction to move toward the rotary shaft 17 of the engaging member 16, against the biasing force of the spring 22, and thus, the roller 20 carried thereon releases the projection 16b of the engaging member 16 from engagement therewith. When the projection 16b of the engaging member 16 is released from engagement with the roller 20, said engaging member rotates in a counterclockwise direction under the biasing force of the spring 18 and the pawl 16a thereof engages the ratchet tooth la, stopping the rotation of the selector wheel 1 as shown in FIG. 2. At the column adjacent the one shown in FIG. 1, the second restraining member 198 is driven by the electromagnet means 268 to move in a direction opposite to the moving direction of the first restraining member 19A, i.e. in a direction to move away from the rotary shaft 17 of the engaging member 16 and the roller 20 carried thereon disengages from the projection 16b of the engaging member 16 as shown in FIG. 4. The engaging member 16 rotates in a counterclockwise direction under the biasing force of the spring 18 and the pawl 16a thereof engages the ratchet tooth 1a of the selector wheel 1 at that column, holding said selector wheel 1 in the selected position. Thus, each selector wheel 1 is held stationary in its selected position. At the column where the selector wheel 1 is held against rotation, the drive bar 3 only moves off the recess 4a of the clutch member 4 and makes a rotational motion to the end of its stroke against the biasing force of the U-shaped spring 7, with the selector wheel 1 being held stationary.

When the character to be typed has been selected at each column in the manner described, the positioning member 14 is moved into the recess between the adjacent teeth 9a of the type wheel 9 as shown in FIG. 2 and thus, the selected types 9b at the respective columns are registered with each other. Thereafter, the characters carried on the respective types are typed on the typing paper 12 by the action of the platen 13. Upon completion of the typing operation, the respective engaging members 16 are returned to the original positions by a common clear bar (not shown) and the projection 16b of each engaging member 16 is disengaged from the associated roller 20. Therefore, the restraining members 19A, 19B are returned to the original positions under the biasing forces of the springs 22 while each one of them is rotating in the opposite direction with respect to the adjacent one. The positioning member 14 is also returned to its original position by a cam (not shown). Thereafter, the drive bar 3 moves in the direction of the arrow B in FIG. 2, returning the selector wheel 1 at each column to its original position where it abuts against the stopper 15, as shown in FIG. 1. One typing operation is completed by this step.

Now, the manner of restraining engagement and disengagement betwen the projection 16b of the engaging member and the roller carried on the restraining member 19 will be described in detail with reference to FIG. 9. FIG. 9 shows in an enlarged scale the relative positions of the first restraining member 19A and the engaging member 16, the solid line indicating the first restraining member in the restraining position and the broken line indicating the same in the releasing position. The arc f concentric with the shaft 21 indicates the moving path of the roller 20, and the projection 16b is so shaped that the angle a formed by the tangential line d of the arcf, passing the center of the roller 20 in the restraining position and extending in the moving direction of said roller 20, and the extension e of the sliding surface of the projection 16b, extending also in the moving direction of the roller 20, opens in the direction of movement of the roller 20 for releasing the engaging member 16. Thus, it will be understood that the rotational force of the engaging member 16, caused by the spring 18, acts so as to assist in releasing motion of the first restraining member 19A. Here, it should be noted that the angle or cannot be made so large, for the reason that the restraining member 19A is required to hold the engaging member 16 in its restrained position until it receives the releasing signal. At the point when the releasing motion has been completed, the roller 20 falls off the projection 16b relative to said projection and takes the position indicated by the broken line in FIG. 9, and can be held in that position even after the current supply to the electromagnet means 26A is interrupted. This is advantageous in that the electric energy to be supplied to the electromagnet means 26A can be saved and in that a stable releasing motion can be obtained.

A more preferred embodiment in which all of the restraining members 19A, 19B, 19C, 19D respectively are driven by the aforesaid four electromagnet means 26A, 26B, 26C, 26D, will be described with reference to FIGS. 11 and 12.

In the illustration of FIG. 11, the restraining member 19A when driven by the electromagnet means 26A, makes a pivotal movement in a direction to get close to the shaft 17 of the engaging member 16 (see FIGS. 1 and 2), releasing said engaging member 16 from restrainment. The restraining member 19D is driven by the electromagnet means 26D, arranged in a position substantially in axial symmetry with the electromagnet means26A, and makes a pivotal movement in a direction to get close to the shaft 17 (see FIG. 8), releasing the engaging member 16 from restrainment. The restraining member 198 is driven by the electromagnet means 268, arranged in a position substantially in axial symmetry with the electrom agnet means 26A, 26B, and makes a pivotal movement in a direction to move away from the shaft 17 (see FIG. 3), releasing the engaging member 16 from restrainment. The restraining member 19C is driven by the electromagnet means 26C, arranged in a position substantially in point symmetry with the electromagnet means 268 and substantially in axial symmetry with the electromagnet means 26A, 26D, and makes a pivotal movement in a direction to move away from the shaft 17 (see FIG. 7), releasing the engaging member 16 from restrainment. Such arrangement as described above enables one electromagnet means to be arranged striding over the four restraining members, and hence, enables each electromagnet means to be accommodated in a smaller space with respect to the direction in which the types characters are spaced from each other. Further, it becomes possible to eliminate one of the four assemblies, each comprising the restraining members and the corresponding engaging member and electromagnet means, and to use three of such assemblies.

According to the printer of the invention. as may be understood from the foregoing description, the space interval between adjacent ones of the typed characters or the so-called character pitch can be reduced and, therefore, the excess space between types characters heretofore unavoidable by reason of the construction of the conventional printer can be eliminated. The printer according to the invention can be designed advantageously in respect of voltage fluctuation, heat generation, heat radiation, attraction time of electromagnet means and attractive force, because a sufficiently large space becomes available in the printer for the accommodation of the electromagnet means, and therefore, has the advantages that the power consumption can be saved and that the operational reliability can be enhanced. The printer of the invention has the further remarkable advantages that the uniformalization of the component parts can be promoted and that it is simple in construction and can be assembled easily.

We claim:

1. A printer comprising a plurality of typewheels mounted for rotation in side by side relation to one another, a plurality of movable selector elements disposed in side by side relation to one another adjacent said typewheels respectively, operator means for driving said selector elements, each of said selector elements having a first toothed portion thereon in driving engagement with one of said typewheels and also having a second toothed portion of ratchet configuration thereon, a plurality of electromagnets each of which is adapted to be energized when an associated one of said typewheels is rotated to a desired printing position, a plurality of restraining elements rotatably supported on a common shaft, each of said restraining elements being disposed adjacent one of said electromagnets for rotatable movement about said shaft when its associated electromagnet is energized, a plurality of engaging members rotatably supported on a further shaft, each of said engaging members including a portion disposed adjacent one of said restraining elements whereby each of said restraining elements restrains its associated engaging member against rotation about said further shaft when its associated electromagnet is de-energized and releases said engaging member for rotation about said further shaft when said associated electromagnet is energized, a plurality of springs coupled to said engaging members respectively for biasing said engaging members in a direction toward the ratchet toothed portion of its associated selector element for causing each of said engaging elements to engage one of said ratchet toothed portions when said engaging element is released from restraint by energization of the electromagnet and restraining element associated with said engaging member, said plurality of restraining elements comprising the plurality of first restraining elements positioned relative to their associated electromagnets for rotation in a predetermined first direction about said common shaft to release their associated engaging members from restraint, and a plurality of second restraining elements, interleaved in position relative to said first restraining elements, and positioned relative to their associated electromagnets for rotation in a predetermined second direction, opposition to said first direction, about said common shaft to release their associated engaging members from restraint.

2. The printer of claim 1 wherein said plurality of first restraining elements and said plurality of second restraining elements are positioned adjacent one another in groups of four restraining elements, each of said groups comprising one restraining element which is driven by a first electromagnet for rotation about said common shaft to release its associated engaging member from restraint, a fourth restraining element which third restraining elements. 

1. A printer comprising a plurality of typewheels mounted for rotation in side by side relation to one another, a plurality of movable selector elements disposed in side by side relation to one another adjacent said typewheels respectively, operator means for driving said selector elements, each of said selector elements having a first toothed portion thereon in driving engagement with one of said typewheels and also having a second toothed portion of ratchet configuration thereon, a plurality of electromagnets each of which is adapted to be energized when an associated one of said typewheels is rotated to a desired printing position, a plurality of restraining elements rotatably supported on a common shaft, each of said restraining elements being disposed adjacent one of said electromagnets for rotatable movement about said shaft when its associated electromagnet is energized, a plurality of engaging members rotatably supported on a further shaft, each of said engaging members including a portion disposed adjacent one of said restraining elements whereby each of said restraining elements restrains its associated engaging member against rotation about said further shaft when its associated electromagnet is de-energized and releases said engaging member for rotation about said further shaft when said associated electromagnet is energized, a plurality of springs coupled to said engaging members respectively for biasing said engaging members in a direction toward the ratchet toothed portion of its associated selector element for causing each of said engaging elements to engage one of said ratchet toothed portions when said engaging element is released from restraint by energization of the electromagnet and restraining element associated with said engaging member, said plurality of restraining elements comprising the plurality of first restraining elements positioned relative to their associated electromagnets for rotation in a predetermined first direction about said common shaft to release their associated engaging members from restraint, and a plurality of second restraining elements, interleaved in position relative to said first restraining elements, and positioned relative to their associated electromagnets for rotation in a predetermined second direction, opposition to said first direction, about said common shaft to release their associated engaging members from restraint.
 2. The printer of claim 1 wherein said plurality of first restraining elements and said plurality of second restraining elements are positioned adjacent one another in groups of four restraining elements, each of said groups comprising one restraining element which is driven by a first electromagnet for rotation about said common shaft to release its associated engaging member from restraint, a fourth restraining element which is driven by a fourth electromagnet disposed adjacent said fourth restraining element at a position substantially in point symmetry with said first electromagnet relative to said common shaft to release the engaging element associated with said fourth restraining element, and second and third restraining elements disposed respectively adjacent second and third electromagnets and positioned respectively in line symmetry with said first and fourth electromagnets to release the engaging members associated with said second and third restraining elements. 